Five years from now disk-based movies will be a niche market for those of us who want the very highest quality video and audio (1080p, lessless 7.1 audio). Most everyone else will be doing things like AppleTV rentals, Netflix download rentals, etc. The industry will figure out how to make it simple and attractive to consumers.There is a distinct difference between how people listen to music these days and how they watch movies. People want to be able carry their music with them and listen to songs over and over again.....
That's my prediction.
Personally, I don't feel the need to own movies and I think a lot of people are like that (look at Netfix's success). I just do because there's no good rental model for high quality downloadable movies. I have over 400 DVDs and have started my Blu-ray collection with about 20 disks, but I would be happier to just not have them and rent them on demand, if the quality and price are right (which they aren't yet).